The art has provided various indexing devices mountable on a work surface of machine tools that are useful for holding work pieces at selected angular positions for machine tool applications. However, prior art indexers have had several disadvantages including, for example, excessive weight, complicated machine tool interface, imprecise angular locking, the inability to sequentially index in separate directions, or the inability to be easily customized or adapted for different applications. Accordingly, there is a need for an indexer that addresses some or all of these problems and does so in an efficient, reliable, and precise manner.